1. Technical Field
The present disclosure relates generally to a DC-to-AC power conversion system and a method of operating the same, and more particularly to a DC-to-AC power conversion system and a method of operating the same which are provided to reduce leakage currents caused by parasitic capacitance voltages.
2. Description of Related Art
Reference is made to FIG. 1 which is a circuit diagram of a prior art full-bridge inverter. Under the zero voltage condition, the full-bridge inverter is provided to decouple the DC side and the AC side. In theory, under the zero voltage condition, the voltage between point A and point N (referred to as “VAN” hereinafter) and the voltage between point B and point N (referred to as “VBN” hereinafter are a half of the DC voltage Vdc, namely, VAN=VBN=1/2 Vdc. Hence, the common mode voltage of the point A and the point B is fixed to reduce leakage currents Icp1, Icp2 caused by parasitic capacitance voltages. However, the leakage current Icp1, Icp2 would be rapidly changed once the parasitic capacitance voltages of the parasitic capacitances Cp1, Cp2 significantly change because the zero voltage conditions occur under the exchanging phase of the AC source. That is, the leakage currents get larger as the variation of the parasitic capacitance voltages gets larger. In fact, the voltage VAN and the voltage VBN are not exactly equal to a half of the DC voltage Vdc because the characteristics of circuit components and the parasitic capacitances Cp1, Cp2 are not identical, so that the common mode voltage of the point A and the point B is not fixed.
Accordingly, it is desirable to provide a DC-to-AC power conversion system and a method of operating the same so that an auxiliary switch circuit is used to provide energy-releasing loops. Also, the auxiliary switch circuit is connected to the neutral point to significantly reduce leakage currents caused by parasitic capacitance voltages.